text: The power law model is used to display the behavior of Newtonian and non-Newtonian fluids and measures shear stress as a function of strain rate.
  The relationship between shear stress, strain rate and the velocity gradient for the power law model are:
  where
  * is the absolute value of the strain rate to the (n−1) power;
  *  is the velocity gradient;
  * n is the power law index.
  If
  * n < 1 then the fluid is a pseudoplastic.
  * n = 1 then the fluid is a Newtonian fluid.
  * n > 1 then the fluid is a dilatant.